I had something similar happen in my game recently.  I had a couple going on a woohoo scavenger hunt (woohoo in as many different locations as possible).
For the first one, they went to a clothing store and woohooed in a changing booth.  This was their first public wohoo.  The memories from that were messed up.  Instead of woohooed with (name) I got woohooed with odd things, like controllers.  This couple were kinkier than I thought 

  I fixed the memories in SimPE so that they actually referred to the sim they'd woohooed with, and the problem was solved.
I know you said you'd checked the memories in SimPE.  If I were you, I'd double check the memories in SimPE to see that they actually refer to sims and not unusual objects.